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Enum member std.range.primitives.hasSwappableElements

Returns true if R is an input range and has swappable elements. The following code should compile for any range with swappable elements.

enum hasSwappableElements(R) = isInputRange!R && is(typeof((ref R r) => swap(r.front, r.front))) && (!isBidirectionalRange!R || is(typeof((ref R r) => swap(r.back, r.front)))) && (!isRandomAccessRange!R || is(typeof((ref R r) => swap(r[0], r.front))));
R r;
static assert(isInputRange!R);
swap(r.front, r.front);
static if (isBidirectionalRange!R) swap(r.back, r.front);
static if (isRandomAccessRange!R) swap(r[0], r.front);

Example

static assert(!hasSwappableElements!(const int[]));
static assert(!hasSwappableElements!(const(int)[]));
static assert(!hasSwappableElements!(inout(int)[]));
static assert( hasSwappableElements!(int[]));

static assert(!hasSwappableElements!( string));
static assert(!hasSwappableElements!(dstring));
static assert(!hasSwappableElements!( char[]));
static assert( hasSwappableElements!(dchar[]));

Authors

Andrei Alexandrescu, David Simcha, and Jonathan M Davis. Credit for some of the ideas in building this module goes to Leonardo Maffi.

License

Boost License 1.0.